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Gain measurements of very electrically small antennas (VESAs) present special challenges. These antennas radiate with poor efficiency, and great care is needed to make a suitable gain measurement using radiative techniques. This paper presents a novel gain measurement technique based upon the observation that the gain of well-matched VESAs is proportional to electrical volume and antenna quality factor...
A polarization Agile printed antenna was successfully designed, prototyped and experimentally characterized for GPS and Iridium applications. Its structure is simple and consists on two radiating rectangular loops. The proposed single-feed dipole is able to toggle either between Linear Polarization (LP) and circular polarization (CP) or between two CP (Right Hand (RHCP) and Left Hand Circular Polarization...
In this paper, two UHF meandered line antennas have been designed, simulated, fabricated and measured. These are, the meandered antenna and the spiral antenna for RFID and WSN's applications. A MoM-based electromagnetic simulator has been utilized to simulate the designed antennas. The antennas have been fabricated and their performances have been tested in anechoic chamber for more accurate results...
A novel and simple design of dielectric resonator antenna (DRA) is presented to achieve reconfiguration in bandwidth. The proposed antenna uses a rectangular DRA element of permittivity 10.2. The DRA is fed by an aperture coupled microstrip line printed on a 3.2 dielectric material with a thickness of 0.762mm. The antenna uses a hybrid radiator to get a wider bandwidth. HPND-4005 PIN diode is used...
This paper presents a small aperture shaped ring focus reflector antenna that covers the frequency band from 7.9 GHz to 9.1 GHz, featuring a wide bandwidth, low VSWR and low-cross-polarization levels. The proposed antenna is composed of a feed horn, a polarizer, a main- and sub- reflector. To validate the concept, an antenna prototype is manufactured and then tested. Both simulated and measured results...
In this work, a stacked ring spiral antenna has been proposed, the metallic ring is stacked behind the spiral antenna with the help of FR-4 substrate (dielectric constant=4.3 and loss tangent 0.025), after the ring attachment lowest frequency of spiral antenna is down shifted by 590 MHz. The size miniaturization is 42.5% with improved axial ratio.
This paper presents first how to use the wires of a woman's bra to achieve off-body transmission at 2.4 GHz. The arrangement of the curved wires of a bra is used as a dipole radiating in free space when the length of the wires is progressively increased. The obtained radiation patterns are compared with the radiated fields of straight dipoles having the same length. Then, torso and breast phantoms...
The role of experimental measurements in the engineering design paradigm of modern indoor wireless communication systems is considered herein. Several studies undertaken at the University of Auckland are used to demonstrate the key role that measurements play, both in terms of validation of analytical and/or numerical models, and to gain insight into the key features of the propagation process that...
We consider bundles of conducting Carbon Nanotubes as antennas to operate in the sub-terahertz range of frequencies. A transcendental equation for the complex propagation parameter of the electric current on the antenna is derived. Therefore, the resonant length of the antenna is obtained along with the radiation resistance and the radiation efficiency. Both the single wall (SWCNT) and the multiple...
In a reverberation chamber (RC), the averaged uniform electromagnetic fields are traditionally generated by metallic stirrers, which leads to a long measurement time and a quite districted working volume. How to optimize the stirrers has been a problem for many years. In this paper, we propose a conceptually different approach, e.g., electrical tuning method, to stir a reverberation chamber, our novel...
A tunable reflectarray phase-shifting cell, designed for a resonance frequency of 5.6 GHz, is presented. The cell is based on a simple slot topology and loaded by a ferroelectric thin film capacitor of 60% tunability under 400 kV/cm bias electric field. The cell provides 245 degrees of phase-shifting.
Topic of this paper is the efficient modelling and simulation of state-of-the-art roof antennas employed for vehicles of the AUDI AG. In the investigated roof antenna, several services are joined within one antenna assembly covered by a common housing. To investigate whether the antenna fulfills all specifications concerning scattering parameters and radiation patterns, the antenna needs to be simulated...
In this letter we have applied a new anisotropic zero index metamaterial (ZIM) structure to the quasi-Yagi antenna to achieve a high-directivity quasi-Yagi antenna. Simulation results show that the antenna gain increases for a frequency range over which the proposed metamaterial structure exhibits ZIM properties (10.3–11.7 GHz).
The work at hand explores the chipless RFID coding enhancement via the employment of the characteristic mode theory. The presented results are comparable in performance with some of the state of the art ones giving confidence that much better coding density can be achieved.
The electromagnetic performance of a flexible knitted waveguide is examined. The waveguide is designed to operate in the X- band region and is manufactured by knitting a conducting yarn in the form of the sleeve. Measured data on transmission and return loss are presented and compared to simulated results.
This paper presents a polarization reconfigurable printed loop antenna which could alter its polarization states electronically to right-hand circular polarization (RHCP), left-hand circular polarization (LHCP) or linear polarization (LP). By inserting four PIN diodes into the symmetric gaps of a dual-loop planar antenna, the proposed antenna can switch its polarization status by controlling the on-off...
A novel approach to the modelling of passive intermodulation (PIM) generation in passive components with distributed weak nonlinearities is outlined. Based upon the formalism of X-parameters, it provides a unified framework for co-design of antenna beamforming networks, filters, combiners, phase shifters and other passive and active devices containing nonlinearities at RF front-end. The effects of...
This paper presents results of an extensive parametric study, based on Electromagnetic simulation, for square loop type frequency selective surfaces (FSS). Consideration was given to the physical attributes of the FSS, such as the loop dimensions and spacing, substrate thickness and dielectric properties, for several frequencies and plane wave incident angles. Correlation analysis and evaluation of...
This paper presents a near field communication (NFC) antenna that is printed directly on a ferrite substrate using a silver inkjet printing process. Such a silver inkjet printed ferrite NFC antenna provides a minimum substrate thickness, a good operation on metal objects, and a small assembly effort. The NFC antenna performance is analysed by measurements based on the ISO/IEC standard 10373-6 for...
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